Alien invaders

[Elton]

It will be interesting to see if Steve Burke picks up on this thread.

 

By introducing a few pike into one of his waters, and I mean just a few, he stopped the appearance of small carp. It could be something as simple as that.

 

There are certainly regional variations, I'm sure, as apart from some notable exceptions, carp do seem bigger down here. I'd be amazed, though, if it stopped them from breeding. The reason carp were brought over here was to be farmed for food, which would indicate that they're one of the best breeders.

[Peter Sharpe]

Their at it like rabbits up here to, but don't seem to have the little babies.

I know of a small, spring-fed water where carp used to go through the motions but not produce any fry, but generally speaking they breed like fury. I used to fish a water where in late July, you could catch 2 inch carp on a maggot in the margins within seconds of casting in. By the late autumn there wasn't any evidence that they had ever been there. I think that between them, the carp, perch and grebes manage to wipe out 99% of them.

I have heard that at Claydon and Woburn, it used to be possible to catch juvenile catfish, merely by sweeping a net through the margins. I also know of a lake in South Lincs where they have definitely bred.

[Ken L]

Interesting article/paper.

[lutra]

Interesting article/paper.

Thanks for that Ken, its very interesting.

[gozzer]

Would this list, (taken from the paper in Ken's post), have been the same 20yrs ago?

 

The most commonly angled fishes (and their perceived abundance) in the Thames are (in decreasing

order): common carp, common bream Abramis brama, barbel Barbus barbus, roach Rutilus rutilus, chub Leuciscus cephalus and dace L.leuciscus.

 

I don't think that catfish have been stocked in great enough numbers to have made an impact on river systems ...yet.

But carp don't need to breed that successfully. They have been (and still are) introduced in such large numbers, that they will impact on the resident species without it.

 

John.

[lutra]

But carp don't need to breed that successfully. They have been (and still are) introduced in such large numbers, that they will impact on the resident species without it.

 

John.

Don't know if I'm right or wrong to think this, but if a species has to rely on being stock to sustain its existence (which seems to be the be case to me in a lot of more northern waters for carp), then surely it doesn't pose the same threat as a species that can sustain or expand its own population (breed).

[wayne baker]

It is wierd really as I know of ponds that have contained Carp for 30yrs+ and there are no youngsters. Thing is I knew a chap who kept Koi carp in his pond and they bred no probs. I was thinkin about a passion for angling and how the pond in the estate containing "Harry" and "Fat lady" seemed void of any small Carp or at least it never showed any in the programe.

 

 

 

 

Elton we know they can breed but why in unstocked waters don't you ever see any youngsters ?

Its one of those mysteries. I know a lot of waters with large heads of carp which never seem to have any small fish coming through a good example is Layer pit in Essex I have seen carp feeding on their own fry many.times there over the years. You would think there would be a few come through to adulthood. And another ressie i fish regularly has small carp coming through each year,, There are obviuosly many factors that are envolved etc predation and the like. Maybe carp are just very vunerable and easy prey when small. Im no expert its just my thoughts

[gozzer]

Don't know if I'm right or wrong to think this, but if a species has to rely on being stock to sustain its existence (which seems to be the be case to me in a lot of more northern waters for carp), then surely it doesn't pose the same threat as a species that can sustain or expand its own population (breed).

 

IMO,That would be the case if a small number of a species were introduced.

Carp are a very invasive species, and impact on the environment in many ways, mainly by the way they feed.

The inane stocking policies of the last 20-30 yrs have ensured that a steady supply of carp (type fish) are introduced into our systems, by escapees and by idiots who 'fancy a bit of carping' in their local waters.

I think it was last year that we had an owner of a 'commercial' on here saying that 5000 catfish (among others) had escaped into the system in one flood from his ponds. This was in the East Yorks area. This year I've heard (as yet unconfirmed) that a catfish has been caught on the lower Aire.

OK if it's true then it's only one catfish, (so far).

The area that the escape happened is riddled with this type of water, so I think I might be right to assume that this wasn't an isolated case.

I read a paper recently that there were 7 (I think) strains of carp that are known to reside in the 'wild' in the UK. Many of these are native to places with greater extremes of temperature than we have here, so if they thrive and breed there, then our climate should be no barrier to them. Maybe they haven't had time (or numbers) to 'adjust' the waters to their liking.

 

As to the capture of small carp in 'unstocked' waters, how many have caught small tench from those same types of waters?

We can't judge the actions of 'wild' fish by comparing them with those caught in an artificial environment such as an overstocked commercial.

Even most of the studies done into carp and catfish have been done on captive fish, so even they are no great indicator to the fish's behaviour in a more natural environment.

 

John.

[Dick Dastardly]

One of the reasons you often see small carp fry in the Autumn but not the next year is that they dont survive the winter. Reason being that its often quite late in the summer that the water is warm enough to stimulate the carp to spawn.Being born late they dont have enough time to put on enough weight/grow big enough to over winter.

 

A very common occurance on a lot of the big southern gravel pits whch being quite open cool down very quickly in the winter.Back in the 90's the EA was very keen on aproaching clubs/controlling bodies whose waters had this problem and nettng fry whch they "fostered out" to other smaller,more sheltered waters. Once the fry had grown on a percentage were returned to the origonal water and the remaining left with the "foster" water.

 

Without putting too fine a pont on it the survey Ken pointed to was a load of old ******! Very poorly thought out and a complete waste of money...not that any of us involved cared! Very much a forgone conclussion.

 

Its been mentioned that maybe if the carp dont breed sucsessfully in a water then they are no longer a potential probem. I tend to disagree with that as its not just the fact that they may breed thats a problem.If enough carp are stocked it is the actual effect they can have themselves on both the other fish,the food and indeed the make up of the water. Try keeping a few carp in a tank with some other species. After ony a few days they will have uprooted every piece of weed,started bullying the other fish and generaly "hog" the food!

[Peter M]

It will be interesting to see if Steve Burke picks up on this thread.

 

Or Vagabond as he had a interesting view on carp and catfish on the thread about Zander recently.